1. Field of the Invention
This invention relates to a copper alloy high in abrasion resistance, and more particularly to the copper alloy which is suitable for the powder material of an overlaid layer formed at a frictionally sliding part of an engine, for example, a valve seat or the like in an engine cylinder head formed of aluminum alloy.
2. Description of the Prior Art
Powder materials of an overlaid layer to be formed at a frictionally sliding part of an engine has been proposed in Japanese Patent Provisional Publication No. 8-35027. An example of the powder materials is formed of a copper alloy which consists essentially of 1.0 to 5.0 wt % of aluminum, 0.1 to 5.0 wt % of at least one of vanadium, Niobium and Tantalum in the group Va of the periodic table of elements, 1.0 to 5.0 wt % of silicon, and balance being copper and impurities. Cobalt, iron manganese are optionally added to the copper alloy of the powder material if necessary.
In case of forming the overlaid layer on the base material of aluminum alloy by using the above copper alloy powder material under the action of laser beam, a metallographic structure high in abrasion resistance can be obtained; however, when formation of the overlaid layer under a high power output laser beam is made in order to raise a productivity, dilution of aluminum alloy as the base material occurs providing such a tendency as to result in material defects and material structures low in abrasion resistance.